Copenhagen market cabbage was developed in Denmark in 1909. This heirloom variety is an early producer that forms large, round heads with delicious blue-green leaves suitable for sauerkraut and coleslaw.
The dense cabbage heads grow to be 6-8 inches in diameter and weigh up to 8 pounds with creamy, greenish-white interior leaves.
Because this variety does not tolerate heat, seeds should be started indoors eight weeks before transplanting to the garden. Transplant seedlings outdoors four weeks prior to the last expected frost, or direct sow in midsummer for a fall crop. Provide a constant supply of water and mulch around the plants to preserve coolness and moisture.
Plant seedlings 24-36 inches apart and separate rows by 4 feet.
This variety must be harvested before or after the intense summer heat to prevent cabbage heads from cracking. To harvest, cut the heads at the base of the plant, remove outer leaves, and bring the plant indoors to a cool, dry area. Copenhagen market cabbages store for six months.
Leave a head of cabbage in the garden in autumn. Once it ripens and temperatures dip below 40ºF, dig up the entire plant and store it over the winter in moist sand at a temperature of 40ºF. Replant four to six weeks before the last spring frost. If the head is still firm, cut a deep X in the top to provide an easier exit for the stem. The stem will grow 4-5 feet tall, with many yellow flowers. Allow flowers to mature, then pick seed pods and dry them indoors. Once they dry, crack the pods open with your hands and store the seeds in a cool, dry place for up to five years.